Pierre River Mine Project

HEALTH AENV SIRS 79 – 89
Section 14.1
• the high degree of conservatism incorporated in the consumption patterns of
these residents and the assumed exposure limit.
The RQ values for the cabin and Aboriginal residents were not predicted to
change between the Base Case and Application Case, indicating that all of the
predicted RQ values under the Application Case and PDC are the result of the
Base Case predictions, and that the project is not likely to increase the risk of
long-term exposure to manganese.
Examination of the contributing exposure pathways revealed that consumption of
non-traditional fruits and vegetables represents most (86%) of the predicted RQ
values for the cabin and Aboriginal residents. Lesser contributions were
identified for the ingestion of berries, cattail roots and, in the case of cabin
residents, the ingestion of drinking water. The contribution of each of these
exposure pathways to the RQ values for manganese is shown in
Table AENV 86-6. The contribution from the remaining exposure pathways was
negligible.
Table AENV 86-6: Contribution of Individual Exposure Pathways to Potential Risk
Quotients for Manganese
Contribution
(%)
Exposure Pathway (a) Planned
Base Case Application Case Development Case
ingestion of drinking water (b) Traditional Foods
3 3 3
ingestion of berries 6 6 6
ingestion of cattail roots 2 2 2
Non-Traditional Foods
ingestion of fruit 30 30 30
ingestion of root vegetables 13 13 13
ingestion of leafy vegetables 43 43 43
Note:
(a) The most sensitive life stage was identified as the toddler.
(b) The contribution reported for the ingestion of drinking water is specific to cabin residents. For the Aboriginal
residents, the contribution from the ingestion of drinking water was negligible.
With the exception of the drinking water pathway, all of the contributing
exposure pathways identified above were highly influenced by the measured
background soil concentration of manganese. Regional manganese soil
concentrations ranged from 1.8 to 5,800 mg/kg, with an average concentration of
460 mg/kg. The 95UCLM concentration of 610 mg/kg was used to characterize
background soil concentrations of manganese and subsequently predict
background manganese concentrations in local, natural foods consumed by cabin
and Aboriginal residents.
The assumption that cabin and Aboriginal residents would obtain all (100%) of
their foods (traditional and non-traditional) from local, natural sources, when in
14-30 Shell Canada Limited April 2010
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